DENVER—The Garfield County sheriff’s department says a helicopter has crashed in western Colorado, killing all three people aboard.

Deputy Ward Stowe says the department cannot immediately release the names of those killed in Monday’s crash near Silt. He says witnesses who saw the crash believe the helicopter was carrying a crew inspecting power lines, and that the helicopter snagged a line.

Stowe says the helicopter bore no identifying marks, so it was not immediately clear who owned it or who might have been operating it.